Testing tag attachments to increase the attachment duration of archival tags on baleen whales
Szesciorka, A. R., Calambokidis, J., Harvey, J. T. . 2016. Testing tag attachments to increase the attachment duration of archival tags on baleen whales. Animal Biotelemetry. 4:18 DOI 10.1186/s40317-016-0110-y
Background: As biologging technology has advanced to study whale behavior, various tag attachment methods have been developed. Suction cup attachments were developed for short-term (<24 h) studies using high-resolution archival tags, and implantable or dart attachments were developed for long-term (months) studies using coarseresolution satellite tags. The purpose of this study was to test various tag attachment configurations to increase the deployment duration of archival tags while minimizing potential physical impacts to the whale.
Results: From 2013 to 2015, 31 humpback whales (Megaptera novaeangliae) and 20 blue whales (Balaenoptera musculus) were tagged, allowing us to test 10 tag attachment configurations, grouped as suction cup, suction cup with dart, two-dart configurations with petals, four-dart configurations, and four-dart configurations with petals. Durations resulting from four-dart configurations with petals were greater than suction cup tags for humpback whales (P = 0.04). Durations resulting from four-dart configurations with petals were greater than all other tag attachment types for blue whales (P < 0.04). There was no difference in reaction to tagging by tag attachment type for humpback (P = 0.19) or blue whales (P = 0.24). Tags attached with titanium darts were recovered with 2 darts (5 %) lost and 31 petals (14 %) broken, whereas tags attached with stainless steel darts were recovered with 1 dart (3 %) lost and 2 petals (1 %) broken. Re-sights of three tagged animals up to 34 days after tags detached showed no sign of tearing or swelling at the tag site.
Conclusions: Tag attachments using four darts with petals remained on whales the longest with no increase in reaction to tagging by either species. Heat-treated stainless steel darts resulted in equivalent tag attachment durations as titanium darts but with reduced petal breakage. Attachments with four darts, despite creating additional points of entry for potential bacterial transfer, did not produce signs of tearing or swelling on animals re-sighted up to 34 days after tagging. Attaching archival tags with four stainless steel darts with petals on baleen whales will allow for the collection of weeks of fine-scale data, allowing researchers to answer questions about foraging, daily activity, and diel trends.